肺癌CT普查——疾病分期与肿瘤大小的关系

目的：肺癌分期与肿瘤直径的关系已被证实是一个预后指标，因此被纳入1986年肺癌分类的国际系统。近年来由于CT飞速发展，人们可以诊断出更小的肺癌，于是有人提倡对肺癌Ⅰ期进一步分期，即根据肿瘤直径小于还是大于30mm，将无确切远处淋巴结转移的病例（Ⅰ期病例）细分为Ⅰa和Ⅰb期。在诊断无症状（即潜伏）的肺癌时，CT普查的开展使人们考虑肿瘤大小的预后价值。在此我们对CT普查诊断的无症状潜伏型肺癌作了分期与大小关系的报道。     

The impact of student-generated learning issues on individual study time and academic achievement

OBJECTIVES: The aim of this study was twofold. The first question concerns the way students make use of the learning issues they generate (as strict guidelines or as global guidelines) and whether this changes across years of training. The second question concerned the relationship between the way students make use of learning issues and the time spent on individual study and achievement on two tests of knowledge. DESIGN: A questionnaire was developed, containing seven items that measured to what extent students study strictly according to the student-generated learning issues and six items that measured to what extent students study beyond the student-generated learning issues. The questionnaire also contained one question in which students had to estimate the mean time spent on individual study. Achievement was measured by two forms of tests of knowledge, a block test assessing course content and a progress test assessing long-term functional knowledge. SETTING: Medical School of Maastricht University, the Netherlands. SUBJECTS: Medical students (response=69%) from the problem-based curriculum at the Maastricht University. RESULTS: During their first year students study strictly according to the content of the learning issues, whereas in later years students studied more according to their own learning needs and interests. In addition, students who tended to study beyond the generated learning issues spent more time on individual study and achieved better on both tests. CONCLUSIONS: Students in a problem-based curriculum seem to become better self-directed learners during the years of training.     

Time course of hypo-osmotic swellings of human spermatozoa: evidence of ordered transition between swelling subtypes

The hypo-osmotic swelling test (HOST or HOS test) usually takes into consideration the total HOS response value with no emphasis either on the value of the response subtypes or the response evaluation time. This study investigated the time course of HOS responses and analysed their physiological relevance. Raw semen spermatozoa and Percoll washed spermatozoa were used in the experiment. The morphological changes in the sperm tail were monitored by incubating the spermatozoa in the hypo- osmotic solution for 16 different time periods. The HOS reactive spermatozoa and the type of HOS reaction (swelling subtypes) of the samples subjected to different duration of treatment were identified under a phase contrast microscope. Also the fate of individual spermatozoa in a hypo-osmotic environment were monitored for 30 min. In spermatozoa exposed to a hypo-osmotic solution, the motility lasted usually less than 2 min and motility characteristics were uniquely different from that of the spermatozoa under iso-osmotic conditions. The HOS response development was permanent but the motility loss due to hypo-osmotic shock was reversible up to 1 min of incubation. There was an indication of ordered transition among the HOS swelling subtypes apparently initiating with subtype b destined to c, d, e, f and g. Further, the subtypes a and g showed gradual decrease and increase, respectively, while subtype b showed abrupt initial increase and then gradual decrease. Transition from b to g could be direct or via one or more than one subtypes. Ultrastructure based analysis indicated that HOS response subtypes are the apparent reflection of the differences in the cytoskeletal assembly of the sperm tail and thus may be identifying different physiological variants in the sperm population. These results indicate that shorter incubation is essential to document the kinetics of various HOS responses but the conventional HOS test misses these important HOS features because of lengthy incubation. Since the time course of ordered transition of HOS responses will vary more than the total HOS response in semen of different aetiologies, the importance of HOS response subtypes and response evaluation time should be taken into consideration when applying HOS test.      

Identification and susceptibility testing of Enterobacteriaceae and Pseudomonas aeruginosa by direct inoculation from positive BACTEC blood culture bottles into Vitek 2

Inoculation of an automated system for rapid identification (ID) and antimicrobial susceptibility testing (AST) directly from positive blood culture bottles will reduce the turnaround time of laboratory diagnosis of septicemic patients, which benefits clinical outcome and decreases patient costs. Direct test results, however, must always be confirmed by testing a pure overnight culture, which is the "gold standard." We studied the accuracy of direct testing versus repeat testing in order to investigate the possibility of refraining from repeat testing. We also assessed the clinical risk of reporting results based on direct testing only. We inoculated Vitek 2 (bioMérieux) directly from 410 positive BACTEC 9240 (BD) blood culture bottles containing gram-negative rods and studied the ID and AST results. In a comparison of direct inoculation with the standard method, a total of 344 isolates of Enterobacteriaceae and Pseudomonas aeruginosa were tested, and 93.0% were correctly identified. Of the 39 (10.2%) samples that contained bacilli not identifiable by Vitek 2, only 1 gave a conclusive, correct result. The overall MIC agreement among 312 isolates was 99.2%, with 0.8% very major and 0.02% major error rates. Of only three (polymicrobial) samples, the direct susceptibility pattern would be reported to the clinician as too sensitive. Vitek 2 results obtained from direct inoculation of blood culture bottles containing gram-negative bacilli are safe enough for immediate reporting, provided that ID and AST are consistent. Repeat testing is not necessary, unless Gram stain or overnight subculture results raise doubt about the purity of the culture.     

Rapid detection of toxigenic Clostridium difficile in fecal samples by magnetic immuno PCR assay.

Rapid detection of toxigenic Clostridium difficile in fecal samples was accomplished with the magnetic immuno PCR assay (MIPA). Elaborate DNA extraction techniques were unnecessary. First, we generated a mouse monoclonal antibody (MAb) reactive with only C. difficile, Clostridium sordellii, and Clostridium bifermentans. Then, magnetic beads were coated with the MAb, incubated with fecal samples to allow binding with C. difficile, extracted from the stool with a magnet, and processed in the PCR with primers specific for the toxin B gene. After optimizing MIPA by raising the number of PCR cycles from 35 to 40 and adding Chelex 100 to the PCR mixture, we found a sensitivity of 96.7%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 94.1% when compared with the culture of cytotoxic C. difficile from fecal samples. MIPA is a rapid, easy, and sensitive PCR method for demonstrating the presence of toxigenic C. difficile in stool samples and avoids the disadvantage of elaborate extraction of DNA from fecal samples.